Simplify the expression. $(x^{4}+3x^{3}+4x^{2})(-5x^{4})$
Solution: First use the distributive property. $ x^4 (-5 x^4) + 3 x^3 (-5 x^4) + 4 x^2 (-5 x^4) $ Simplify. $-5x^{8}-15x^{7}-20x^{6}$